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lost compression on 02 xr400

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just bought a used xr400 in great shape but has a good bit of hours on it. The problem is that it seems to not have much compression whiole trying to kick start it. on my other xr400, i could slowly push the kick down a few times until it built compression and then start from the top of the stroke to crank it. This one will not build much compression on the kick start and is a bear to start when cold. the only compression seems to be at the end of the stroke before the kick starter hits the peg. Is this a "compression" problem that could be remidied with new rings or would it be a valve problem. once the bike is running, it does good, but doesn't seem to pull as hard as my last bike. any advice would be greatly appreciated.

Thanks :cry:

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just bought a used xr400 in great shape but has a good bit of hours on it.

how many hours on the bike?

1) could be time to rebuild your top end.

2) you might be losing compression around spark plug (re-tighten)

3) head gasket might be worn out

4) your manual decompression lever might need re-adjusting. is there some slack or play in it or is it tight? if its tight, try disconnecting the cable then kick the engine over to see if you got compression.

btw-i just bought an 02 XR400 myself! it should be delivered in a few weeks. i cant wait to bomb some trails!

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Sometimes the compression release will stick . Just kick through hard a few times to free it. Make sure the compresion release is adjusted properly and adjust the valves for sure.

Cher'o,

Dwight

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Hey Dwight,

It was you Right? Congrats. on the Press you picked up a few issues back in Cycle news. I loved seeing that you were riding a Hodaka Combat Wombat. That was one of my first rides, and they call it Vintage. Man time goes by quick. :cry:

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Hey Guys thanks for the input. as far as the hours go, i know it's on it's second set of dunlops but other than that i'm not sure. as far as the decompression lever, it only "catches" at the last little bit of the pull so the first part of the pull is all slack. i'm not sure how to adjust it. also any help on setting the valves would be great!!. Thanks again.

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have you ever adjusted valves before? its not an "easy" job. i'd take it to a shop and have it done.

-look at these pages for DIY valves-

http://www.dansmc.com/valveclearence.htm

http://www.dansmc.com/valve.htm

-READ THIS FIRST...THE WHOLE THING-

http://www.dansmc.com/compression_test.htm

unless the bike was really, really, really run hard, or not maintained properly, i dont see how the valves need servicing on a 2 year old XR400.

good luck and keep us posted

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Hey Dwight,

It was you Right? Congrats. on the Press you picked up a few issues back in Cycle news. I loved seeing that you were riding a Hodaka Combat Wombat. That was one of my first rides, and they call it Vintage. Man time goes by quick. :cry:

Like that huh ?

How about my friend Rik Smits on his huge Maico 490. He makes it look like a mini bike at 7'4". He is quite a good rider also.

Cher'o,

Dwight

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